Homes or cabins built of logs are often considered desirable for their aesthetics. However, constructing such log structures can present a number of difficulties. For example, it can be difficult to provide corner connection of logs at an intersecting corner that is strong and weather tight, both at initial installation and after the log walls have settled over time.
A known corner connection structure is disclosed in U.S. Pat. No. 5,020,289 (Wrightman). The corner connection of Wrightman provides a dovetail joint between the intersecting logs, and a pair of splines having a ‘figure-8’ cross-sectional profile. However, the structural elements themselves leave seams through which the weather could penetrate. Caulking could be provided for weather-proofing, but caulking has a limited lifespan, and could work loose during natural settling and shrinkage of the logs. Alternatively, gaskets could be provided between the mating faces of the dovetails, but gaskets can be relatively costly and time-consuming to install.
Another corner connection structure is disclosed in U.S. Pat. No. 4,353,191 (Schilbe). The corner connection structure of Schilbe has an obliquely disposed mortise provided adjacent the intersecting region of logs at a corner, and a wooden locking section placed in the mortise. However, by providing the mortise adjacent the intersecting region, rather than within the intersecting region, the locking member is engaged only at its outer ends by the mortise, which may limit the strength and support provided by the locking member. Furthermore, Schilbe does not address the natural settling of the logs that takes place over time. The fit between the mortise and the locking member, as taught by Schilbe, must be sufficient to prevent horizontal movement of the logs relative to the locking member. However, such a tight fit would also inhibit vertical movement of the logs relative to the locking member, which could result in gaps forming between the logs along the height of the walls at the intersecting corner. The weather may then penetrate the corner structure, and moisture could collect within the log structure, between the inside of the walls and the locking member.
Providing through-bolts at corners or at intermediate positions along the lengths of log walls can provide additional strength and support for the walls. Known through-bolt devices are described in U.S. Pat. No. 4,503,647 (Post) and U.S. Pat. No. 4,688,362 (Pedersen et al.). In both of these references, the through-bolt devices include through-bolts extending along the height of the walls, and regular hex nuts at the lower end of the through-bolts for tightening the devices. These devices require access to the hex nuts for wrenches or other tools when assembling or adjusting the through-bolt devices. However, providing such access may be difficult, and may require, for example, fairly large openings cut into the lower sides of the walls. Specially cut panels may then be required to conceal the openings.
It is often convenient in walls constructed of logs that two shorter logs be joined end-to-end to span the length of the wall. A butt joint for connecting logs end-to-end is disclosed in the patent to Wrightman, already noted above. The butt joint according to Wrightman has a two-piece spline with semi-circular lobes on one face and opposing passages on the opposite face. Spikes are driven into the passages to expand the two-piece spline, and provide an interference fit between the lobes of the spline and matching recesses provided in the logs. This butt joint is fairly complex and may be time consuming to assemble. Furthermore, the simultaneous alignment of the passageways and the lobes within the recesses may be difficult to achieve.
Another butt joint is disclosed in U.S. Pat. No. 4,279,108 (Collister, Jr.). The butt joint of Collister Jr. has plastic weather deflectors inserted into a slot, which spans the seam between the adjacent end faces of the logs to be joined. Compressible gasket strips are also provided between the end faces of the adjacent logs. Since no structural joint element engages the logs in a transverse direction, it may be difficult to ensure that the logs connected by this joint are in fact locked to inhibit longitudinal movement. Furthermore, since the gasket strips are installed prior to fixing the logs together, the strips may be damaged during positioning and assembly of the logs.
Openings are often desirable in log walls to accommodate windows, doors, and the like. It may be advantageous to provide special support structures at such openings to facilitate building the walls around the opening, and to provide a suitable mounting means for the structural framing elements of the window or door to be subsequently installed. A known opening support structure is disclosed in U.S. Pat. No. 4,224,772 (Bene et al.). Bene et al. discloses a connection member disposed between the log end faces at the opening and the frame member of a window to be installed in the opening. The connection member is attached to the logs by nails driven through slots in the connection member and into the end grain of the logs, so that relative vertical movement between the connection member and the logs is possible. The frame member of the window is in turn secured to the connection member. Using nails driven into the end grain of the logs may not, however, provide a secure joint because the nails may work loose as the fibers of the wood separate. Furthermore, shrinkage of the logs over time may compromise the strength of the support structure.
In building log walls, the logs themselves can be provided with a particular profile to facilitate alignment of the logs during construction and to increase the strength of the wall. In the above-noted Wrightman patent, a log profile is disclosed in which the tongues and grooves are provided in the upper and lower surfaces of the logs, respectively. The upper and lower surfaces of vertically adjacent logs fit together, providing a seam across the width of the logs. However, at either side of the logs, the profile provides a generally horizontal seam portion which could collect moisture and cause associated wood preservation difficulties.
Another log profile is disclosed in U.S. Pat. No. 3,440,784 (Onjukka). The profile taught by Onjukka has matching tongues and grooves in the upper and lower surfaces of vertically adjacent logs. However, no provision is made for installing seals along the seam between adjacent logs, at a point along the seam between the outer horizontal edges. Accordingly, the weather-proofing of the interface between adjacent logs may be compromised, particularly as the logs shrink and settle over time.
In some log structures having walls constructed of stacked horizontal logs, it can be advantageous to provide vertical posts at the corners of intersecting walls, as well as at intermediate points along the length of a wall. A post-to-log connection structure can be provided for connecting the end faces of the logs to a vertical surface along the post. A known post-to-log connection structure is disclosed in U.S. Pat. No. 4,742,033 (Veech), wherein a vertical spline is inserted into corresponding slots provided in the end faces of the logs and the surface of the post. However, no adjustable fastening means is provided for drawing the post and log ends snugly together.